Case-hardening material.



tion.

No Drawing.

. UNITED STATES PATENT onnron.

HUGH RODM AN, 0F EDGEWOOD, PENNSYLVANIA, ASSIGNOR '10 RODMAN CHEMICAL COMPANY, OF VERONA, PENNSYLVANIA, A. CORPORATION OF PENNSYLVANIA.

I cnsn-nnnnnnme' MATERIAL.

Edgewoodfin the county of Allegheny and State of Pennsylvania, have made a new and useful Invention in Case-Hardening Material, of which the following is a specifica- This invention-relates to the carburizing of steel by dry packing, and discloses a new and improved material therefor.

Charcoal, either alone or mixed with various alkaline substances, is used for carburizing steel. I find that the cellulose portions of wood, when charred, have practically no carburizing activity, while the lig- .nose and fesinous portions are active, even without addition of alkaline substances. In

searching for a cheap and plentiful supply of mater al high in lignose and resin, or the charred. products thereof, I have discovered that the'material hereinafter described meets all requirements, being essentially charred 1 lignose and resin,-and moreover being ava1l-' able in large quantities and at low cost. It

also occursin good, mechanical condition for use as carburizing material.

ThlS new material whlch 1s known as .black ash is a byproduct, or practically a by-product, of the manufacture of wood fiber, especially that made by the alkaline process, and is obtained as follows: Wood chips are digested under heat and pressure inan alkaline solution, say, sodium hydrate, until the cellulose constitutents are freed "of resin and lignose, the cellulose being then washed and bleached for the production of fiber. The tarry, alkaline liquor containing the resin and lignose, (or all the wood constituents but the cellulose) is then concentrated to a heavy syrup and heated in rotary kilns to about 1400 degrees Fahren heit. The kilned product is a heavy black charred mass, granular, consisting of a car bon sponge containing sodium carbonate and sodium 'hydrate. This is leached to re v cover the alkaline contents and the leacher residue ordinarily discarded as worthless.

This leacher residue consists of a light car bon sponge which; when dry, contains-several per cent. of alkali. I have-discovered that these three PIOdllGtSlOf fiber-makin v (the tarry liquid, the kilned-material, an

the leacher residue) are peculiarly active as carburizing materials whenproperly used,

Specification of Letters Patent.

Application filed August 29, 1914. Serial No. 859,228.

but I prefer the residue, as it is practically a waste product, and therefore "cheap. I have, however, made excellent carburizing T material by saturating ordinary wood harcoal with the liquid and by using the kilned product mixed with an'equal volume of ordinary charcoal.

In using leacher residue, I prefer to first dr it, adding, if desired, an energizing agent such for example as ten per cent. of sodium carbonate or fifteen per cent. of calcium carbonate, or both, and then to screen it to the size desired. The material ordinarily occurs in the sizes most used in carburizing operations and requires no crushing. If desired, oil may be added to prevent dusting. -I should add that this leacher residue, quite'aside from its active carburizing qualities, would be of considerable value as a cheap, light, thoroughly charred carbon to directly replace the ordinary wood charcoal in the carburizing art,

and I desire to claim its use because of that consideration, as well as because of its unique actitivy.

, What I claim is:

1. The method of carburizing, which consists in packing the metal to be carburized in the by-product of fiber making, com

monly known as black ash,-'and then in subvjectiing the metal and'the packing material to heat.

2. A method of carburizing steel, which consists in packing the steel part to be carburized in the charred by-products resulting from the manufacture of wood fiberby the alkaline process, and then subjecting the steel part and the packing material to heat.

3. he method of carburizing which consists in packing a metal part to be carburized in amixture of a by-product in the manufacture of wood fiber, known as black ash and an energizing agent and then subiilecting the metal part and the packing to eat.

4. The method of carburizing, which consists in packingthe metal part to be carbu- ,rized .in the charred by-product resultin from the manufacture of wood fiber an then subjecting the metal part and the pack -ing material to a red heat.

' 5. The method of carburizing which con- I duct resulting from the manufacture of PatentedJuly 2, 1918.

- rized in -a mixture of the eharredby-produot resulting from the manufacture of wood fiber andan-energizer and then subjecting the metal part and. the mixture to' a red heat. f i

7. The method' of carburizing which consists in packing the metal part to be' car,- burized in the by-product resulting from the' manufacture of Wood fiber, known as-leacher residue, and then subjecting themetal part andthe packing material to a red. heat.

8. A carburizingmaterial comprising a consists in packing .a

by-product of, wood] fiber manufacture known as black ash and an energizing agent.

f 20 charred resins, charred lignose and an ener- .9. Carburizing material consisting 0 gizing agent. v

10.. The method of carburizing which metal part to be car burized in a mixture of charred resins and lignose. and then subjecting the metal part and the carburizing material to ared; heat.

In. testimony whereof, I have'hereu'nto subscribed my name this 28th day of August, 1914.- v i v HUGH RODMAN. Witnesses C. W. MOG EE, I E. W. MoCALus'rER. 

